P418 qPCR is a useful tool for management and surveillance of hospital contacts in the context of a Candida auris infection

Abstract

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM Objectives Candida auris is an emerging fungal pathogen responsible for hospital outbreaks. It represents a serious threat due to its drug resistance profile and its potential spread within healthcare facilities. Since the global alert by the CDC in 2016, specific control measures are now available to prevent the further spread of the pathogen. These measures should be implemented immediately as soon as a case is identified to prevent patient-to-patient transmission. Until recently culture was the main technique used for the detection of C. auris from patient and environmental samples. Nevertheless, PCR protocols have been reported and commercial kits are now available. Our objectives were to compare culture and PCR in routine for the management of a case of C. auris infection in a hospital setting.MethodsWe report here the case of a patient infected by C. auris following injuries in a public road traffic accident in Dubai. Following the medical evacuation and transfer of the patient to our hospital in Paris, C. auris was isolated from several surgical specimens from the elbow. Identification of the species level was initially performed by MALDI-TOF Mass spectrometry and confirmed by ITS sequencing. Antifungal susceptibility testing was performed by Etest and EUCAST. Surveillance of the index case included bi-weekly surveillance for 2 weeks and then once a week. Contacts were also screened for C. auris colonization once a week by swabbing axilla and groin. Samples were analyzed by standard mycological cultures and a specific C. auris qPCR kit (kit Fungiplex Candida auris®, Bruker).ResultsIn total 133 samples were analyzed for the patient and 52 contacts. For the index case, 14/22 samples were positive in culture for C. auris including elbow biopsies, urine, and axilla, groin, and rectal swabs. Other Candida species (C. albicans, C. krusei) were also recovered from the same samples for the patient. For the contacts, all 111 samples were negative for C. auris by culture, but retrieved several other yeast species (C. albicans, C. glabrata, C. kefyr, C. paraspsilosis, C. tropicalis, Saccharomyces cerevisiae, Trichosporon inkin, and Wickerhamomyces anomalus). By using qPCR, all culture-positive samples were positive (Ct ranged from 29.7 to 38.0, with a median at 31.4). Two culture-negative samples (one biopsy and one axillary swab) were also qPCR-positive. All samples from contacts were negative by qPCR. The strain was resistant to fluconazole (>256 μg/ml) and susceptible to all other tested antifungals (amphotericin B, flucytosine, voriconazole, and caspofungin). Whole genome sequencing of the C. auris strain is in progress to determine the clade.DiscussionThe Fungiplex C. auris qPCR kit showed good sensitivity and specificity, even for the frequent situation of samples growing with two or three Candida species. These results highlight the usefulness of the PCR for surveillance of infected patients as well as for contacts.